The invention resides in a drawing press which is suitable in particular for integration into press working lines, hybrid press set ups or transfer presses for the manufacture automobile body parts.
In the manufacture of automobile body parts or other large area spatially formed metal sheets the first press stage is generally a drawing press which gives an initially planar plate a spatial shape. This is done in a drawing press in which the rim of the metal sheet is clamped in position or which permits the rim to slide toward the plate center in a controlled manner, while the part of metal sheet surrounded by the sheet holder is compressed between a die and a plunger to deform it spatially as desired. For this purpose, drawing presses have been developed wherein the plunger is supported on a press table and the respective die is disposed on the vertically up and down movable stamping tool. The sheet holder surrounds the plunger and is pressed downwardly during the drawing procedure by the rim of the die against the force of a draw cushion. With this basic configuration, the convexly arched sheet side is formed at the top of the sheet part as it is desirable for the follow-up press steps. In the subsequent pressing steps also punching procedures are performed for which, in connection with vehicle body parts, the punching lever must be at the concavely curved side of the metal sheet part. Since turn-over stations between the pressing steps are to be avoided the manufacturing procedure as described herein has become the standard procedure. Manufacturing procedures with bottom dies and top plungers (as well as upper metal sheet down holders) as they are known, for example, from DE 10117578 B4 are rarely used.
Presses of the type as described above, that is with upper dies and lower plunger are known, for example, from DE 10 2006 025271 B3. Since it has been recognized that with this concept at the drawing cushion a large amount of energy is used and generally lost which energy has to be provided by the plunger. Because the plunger has to hold the metal sheet holder down during the drawing procedure the above publication proposed the recuperation of the work or respectively energy expended on the drawing cushion by applying the metal sheet down holding force by means of servomotors and low-friction spindle screw drives. The energy can be retrieved by the servomotors from the drawing cushions during a generator operation of the motors and returned to the power supply.
However, during the energy recuperation energy losses are unavoidable.
It is therefore the object of the present invention to provide a press concept and a conversion process wherein by an orientation of the subsequent press stages, deep draw components can be manufactured with low energy consumption.